Table 5.

Relative risk (RR) with 95% confidence interval (CI) of amyotrophic lateral sclerosis, according to overall lifetime estimated intakea of inorganic Se through drinking water, Reggio Emilia municipality, northern Italy, 1995-2006

Lifetime Se intake (μg)	Cases/controls	RR	95% CI
0	27/68	1.0 (referent)	-
1-9999	6/7	2.1	0.5-9.1
≥10000	8/7	6.4	1.3-31

^aEstimated on the basis of drinking water consumption during the 35-year period before diagnosis in patients and the corresponding period for matched referents.